U.S. patent number 10,091,815 [Application Number 15/213,156] was granted by the patent office on 2018-10-02 for user equipment silencing based on clear channel assessment in shared spectrum.
This patent grant is currently assigned to QUALCOMM Incorporated. The grantee listed for this patent is QUALCOMM Incorporated. Invention is credited to Karl Georg Hampel, Junyi Li, Vincent Douglas Park.
United States Patent |
10,091,815 |
Hampel , et al. |
October 2, 2018 |
User equipment silencing based on clear channel assessment in
shared spectrum
Abstract
Methods, systems, and devices for wireless communication are
described. A wireless device communicating critical or latency
sensitive information may determine that a clear channel assessment
(CCA) has failed in a shared radio frequency (RF) spectrum band.
The device may then transmit a silencing signal in a managed RF
spectrum band, and switch to communicating in the managed band from
transmitting in the shared band. Other wireless devices
communicating with the first device may receive the silencing
signal and may also switch to the managed RF spectrum band. Based
on the silencing signal, user equipments (UEs) not associated with
the critical communications, but also operating in the managed
band, may suspend transmissions in the managed band (e.g., uplink
(UL) data), although they may still receive transmissions in the
managed band (e.g., downlink (DL) data).
Inventors: |
Hampel; Karl Georg (New York
City, NY), Li; Junyi (Chester, NJ), Park; Vincent
Douglas (Budd Lakes, NJ) |
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
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Assignee: |
QUALCOMM Incorporated (San
Diego, CA)
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Family
ID: |
57485958 |
Appl.
No.: |
15/213,156 |
Filed: |
July 18, 2016 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20170171885 A1 |
Jun 15, 2017 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62260081 |
Nov 25, 2015 |
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62260061 |
Nov 25, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
16/14 (20130101); H04W 72/14 (20130101); H04W
74/0808 (20130101); H04L 5/0007 (20130101); H04L
5/0055 (20130101); H04W 74/04 (20130101); H04L
5/14 (20130101); H04W 74/008 (20130101) |
Current International
Class: |
H04J
3/00 (20060101); H04W 74/00 (20090101); H04L
5/00 (20060101); H04W 74/04 (20090101); H04L
5/14 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
ISA/EP, International Search Report and Written Opinion of the
International Searching Authority, Int'l Application No.
PCT/US2016/062918, dated Feb. 23, 2017, European Patent Office,
Rijswijk, NL, 13 pgs. cited by applicant .
Ratasuk et al., "License-Exempt LTE Deployment in Heterogeneous
Network," IEEE, International Symposium on Wireless Communication
Systems (ISWCS), Aug. 28, 2012, pp. 246-250 , XP032263759, DOI:
10.1109/ISWCS. 2012.6328367, Institute of Electrical and
Electronics Engineers. cited by applicant.
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Primary Examiner: Wei; Siren
Attorney, Agent or Firm: Morin; Clint R. Holland &
Hart
Parent Case Text
CROSS REFERENCES
The present application for patent claims priority to U.S.
Provisional Patent Application No. 62/260,081 by Hampel et al.,
entitled "User Equipment Silencing Based on Clear Channel
Assessment in Unlicensed Spectrum," filed Nov. 25, 2015, assigned
to the assignee hereof, and to U.S. Provisional Patent Application
No. 62/260,061 by Hampel et al., entitled "User Equipment Silencing
Based on Transmission Failure in Unlicensed Spectrum," filed Nov.
25, 2015, assigned to the assignee hereof.
Claims
What is claimed is:
1. A method of wireless communication comprising: determining, by a
wireless device, a clear channel assessment (CCA) in a shared radio
frequency (RF) spectrum band has failed, wherein a radio access
technology (RAT) operating in the shared RF spectrum band is
synchronized with a RAT operating in a managed RF spectrum band;
transmitting, by the wireless device, a silencing signal in the
managed RF spectrum band indicating that at least one neighboring
user equipment (UE) is to suspend uplink (UL) transmission in the
managed RF spectrum band, wherein transmitting the silencing signal
is based at least in part on the determination; and transmitting,
by the wireless device, a message in the managed RF spectrum band
based at least in part on the silencing signal.
2. The method of claim 1, further comprising: determining that a
subsequent CCA in the shared RF spectrum band has succeeded after
the CCA; and transmitting a subsequent message in the shared RF
spectrum band based at least in part on the determination that the
subsequent CCA has succeeded.
3. The method of claim 1, further comprising: determining that a
subsequent CCA in the shared RF spectrum band has failed after the
CCA; transmitting a subsequent silencing signal in the managed RF
spectrum band based at least in part on the determination that the
subsequent CCA has failed; and transmitting a subsequent message in
the shared RF spectrum band based at least in part on the
subsequent silencing signal.
4. The method of claim 1, further comprising: performing the CCA in
a time slot prior to a first subframe of a frame structure, wherein
the message is transmitted in the first subframe.
5. The method of claim 1, wherein transmitting the silencing signal
in the managed RF spectrum band comprises: transmitting the
silencing signal during a first time slot of a subframe of a frame
structure of the managed RF spectrum band based at least in part on
the determination.
6. The method of claim 1, wherein the silencing signal comprises a
multitone orthogonal frequency division multiplexing (OFDM) signal,
a pseudonoise (PN) signal, or a constant amplitude zero
autocorrelation (CAZAC) signal.
7. The method of claim 1, wherein the message comprises information
for a mission critical application or for a control
application.
8. The method of claim 1, wherein the managed RF spectrum band
comprises a portion of a system bandwidth of a wireless wide area
network (WWAN).
9. The method of claim 1, wherein time resources of the managed RF
spectrum band are organized according to a time division duplex
(TDD) configuration.
10. A method of wireless communication comprising: identifying, by
a user equipment (UE), resources for an uplink (UL) transmission
associated with a first radio access technology (RAT) operating in
a managed radio frequency (RF) spectrum band, wherein the first RAT
operating in the managed RF spectrum band is synchronized with a
second RAT operating in a shared RF spectrum band; receiving, by
the UE and from a wireless device, a silencing signal in the
managed RF spectrum band indicating that at least one neighboring
user equipment (UE) is to suspend UL transmission in the managed RF
spectrum band, wherein receiving the silencing signal is during a
time period including the identified resources, and wherein
transmitting the silencing signal is based at least in part on a
determination that a clear channel assessment (CCA) has failed; and
suspending, by the UE, transmission in the managed RF spectrum band
during the time period based at least in part on the silencing
signal.
11. The method of claim 10, further comprising: receiving an UL
grant, wherein the resources are identified based at least in part
on the UL grant.
12. The method of claim 10, further comprising: receiving a
downlink (DL) transmission during the time period based at least in
part on a DL grant.
13. The method of claim 10, further comprising: receiving an UL
grant for a subsequent time period; and resuming transmission in
the managed RF spectrum band during the subsequent time period
based at least in part on the UL grant.
14. A method of wireless communication comprising: receiving, by a
first wireless device, a silencing signal in a managed radio
frequency (RF) spectrum band indicating that at least one
neighboring user equipment (UE) is to suspend uplink (UL)
transmission in the managed RF spectrum band, wherein the silencing
signal is based at least in part on a determination that a clear
channel assessment (CCA) has failed, and wherein a first radio
access technology (RAT) operating in the managed RF spectrum band
is synchronized with a second RAT operating in a shared RF spectrum
band; and switching, by the first wireless device, from receiving
transmissions in the shared RF spectrum band by a second wireless
device to receiving transmissions in the managed RF spectrum band
by the second wireless device, wherein the second wireless device
is a source of the silencing signal and the switching is based at
least in part on the silencing signal.
15. The method of claim 14, further comprising: powering up a radio
for the managed RF spectrum band; and listening, using the radio,
for the silencing signal in the managed RF spectrum band during a
first portion of a subframe of a radio frame structure.
16. An apparatus for wireless communication comprising: means for
determining a clear channel assessment (CCA) in a shared radio
frequency (RF) spectrum band has failed, wherein a radio access
technology (RAT) operating in the shared RF spectrum band is
synchronized with a RAT operating in a managed RF spectrum band;
means for transmitting a silencing signal in the managed RF
spectrum band indicating that at least one neighboring user
equipment (UE) is to suspend uplink (UL) transmission in the
managed RF spectrum band, wherein transmitting the silencing signal
is based at least in part on the determination; and means for
transmitting a message in the managed RF spectrum band based at
least in part on the silencing signal.
17. The apparatus of claim 16, further comprising: means for
determining that a subsequent CCA in the shared RF spectrum band
has succeeded after the CCA; and means for transmitting a
subsequent message in the shared RF spectrum band based at least in
part on the determination that the subsequent CCA has
succeeded.
18. The apparatus of claim 16, further comprising: means for
determining that a subsequent CCA in the shared RF spectrum band
has failed after the CCA; means for transmitting a subsequent
silencing signal in the managed RF spectrum band based at least in
part on the determination that the subsequent CCA has failed; and
means for transmitting a subsequent message in the shared RF
spectrum band based at least in part on the subsequent silencing
signal.
19. The apparatus of claim 16, further comprising: means for
performing the CCA in a time slot prior to a first subframe of a
frame structure, wherein the message is transmitted in the first
subframe.
20. The apparatus of claim 16, wherein the means for transmitting
the silencing signal in the managed RF spectrum band comprises:
means for transmitting the silencing signal during a first time
slot of a subframe of a frame structure of the managed RF spectrum
band based at least in part on the determination.
21. The apparatus of claim 16, wherein the silencing signal
comprises a multi-tone orthogonal frequency division multiplexing
(OFDM) signal, a pseudo-noise (PN) signal, or a constant amplitude
zero autocorrelation (CAZAC) signal.
22. The apparatus of claim 16, wherein the message comprises
information for a mission critical application or for a control
application.
23. The apparatus of claim 16, wherein the managed RF spectrum band
comprises a portion of a system bandwidth of a wireless wide area
network (WWAN).
24. The apparatus of claim 16, wherein time resources of the
managed RF spectrum band are organized according to a time division
duplex (TDD) configuration.
25. An apparatus for wireless communication comprising: means for
identifying resources for an uplink (UL) transmission associated
with a first radio access technology (RAT) operating in a managed
radio frequency (RF) spectrum band, wherein the first RAT operating
in the managed RF spectrum band is synchronized with a second RAT
operating in a shared RF spectrum band; means for receiving, from a
wireless device, a silencing signal in the managed RF spectrum band
indicating that at least one neighboring user equipment (UE) is to
suspend UL transmission in the managed RF spectrum band, wherein
receiving the silencing signal is during a time period including
the identified resources, and wherein the silencing signal is based
at least in part on a determination that a clear channel assessment
(CCA) has failed; and means for suspending transmission in the
managed RF spectrum band during the time period based at least in
part on the silencing signal.
26. The apparatus of claim 25, further comprising: means for
receiving an UL grant, wherein the resources are identified based
at least in part on the UL grant.
27. The apparatus of claim 25, further comprising: means for
receiving a downlink (DL) transmission during the time period based
at least in part on a DL grant.
28. The apparatus of claim 25, further comprising: means for
receiving an UL grant for a subsequent time period; and means for
resuming transmission in the managed RF spectrum band during the
subsequent time period based at least in part on the UL grant.
29. An apparatus for wireless communication comprising: means for
receiving, from a wireless device, a silencing signal in a managed
radio frequency (RF) spectrum band indicating that at least one
neighboring user equipment (UE) is to suspend uplink (UL)
transmission in the managed RF spectrum band, wherein the silencing
signal is based at least in part on a determination that a clear
channel assessment (CCA) has failed, and wherein a first radio
access technology (RAT) operating in the managed RF spectrum band
is synchronized with a second RAT operating in a shared RF spectrum
band; and means for switching from receiving transmissions in the
shared RF spectrum band by the wireless device to receiving
transmissions in the managed RF spectrum band by the wireless
device, wherein the wireless device is a source of the silencing
signal and the switching is based at least in part on the silencing
signal.
30. The apparatus of claim 29, further comprising: means for
powering up a radio for the managed RF spectrum band; and means for
listening, using the radio, for the silencing signal in the managed
RF spectrum band during a first portion of a subframe of a radio
frame structure.
31. An apparatus for wireless communication, comprising: a
processor; memory in electronic communication with the processor;
and instructions stored in the memory and operable, when executed
by the processor, to cause the apparatus to: determine a clear
channel assessment (CCA) in a shared radio frequency (RF) spectrum
band has failed, wherein a radio access technology (RAT) operating
in the shared RF spectrum band is synchronized with a RAT operating
in a managed RF spectrum band; transmit a silencing signal in the
managed RF spectrum band indicating that at least one neighboring
user equipment (UE) is to suspend uplink (UL) transmission in the
managed RF spectrum band, wherein transmitting the silencing signal
is based at least in part on the determination; and transmit a
message in the managed RF spectrum band based at least in part on
the silencing signal.
32. The apparatus of claim 31, wherein the instructions are further
operable to cause the processor to: determine that a subsequent CCA
in the shared RF spectrum band has succeeded after the CCA; and
transmit a subsequent message in the shared RF spectrum band based
at least in part on the determination that the subsequent CCA has
succeeded.
33. The apparatus of claim 31, wherein the instructions are further
operable to cause the processor to: determine that a subsequent CCA
in the shared RF spectrum band has failed after the CCA; transmit a
subsequent silencing signal in the managed RF spectrum band based
at least in part on the determination that the subsequent CCA has
failed; and transmit a subsequent message in the shared RF spectrum
band based at least in part on the subsequent silencing signal.
34. The apparatus of claim 31, wherein the instructions are further
operable to cause the processor to: perform the CCA in a time slot
prior to a first subframe of a frame structure, wherein the message
is transmitted in the first subframe.
35. An apparatus for wireless communication, comprising: a
processor; memory in electronic communication with the processor;
and instructions stored in the memory and operable, when executed
by the processor, to cause the apparatus to: identify resources for
an uplink (UL) transmission associated with a first radio access
technology (RAT) operating in a managed radio frequency (RF)
spectrum band, wherein the first RAT operating in the managed RF
spectrum band is synchronized with a second RAT operating in a
shared RF spectrum band; receive, from a wireless device, a
silencing signal in the managed RF spectrum band indicating that at
least one neighboring user equipment (UE) is to suspend UL
transmission in the managed RF spectrum band, wherein receiving the
silencing signal is during a time period including the identified
resources, and wherein the silencing signal is based at least in
part on a determination that a clear channel assessment (CCA) has
failed; and suspend transmission in the managed RF spectrum band
during the time period based at least in part on the silencing
signal.
36. The apparatus of claim 35, wherein the instructions are further
operable to cause the processor to: receive an UL grant, wherein
the resources are identified based at least in part on the UL
grant.
37. The apparatus of claim 35, wherein the instructions are further
operable to cause the processor to: receive a downlink (DL)
transmission during the time period based at least in part on a DL
grant.
38. The apparatus of claim 35, wherein the instructions are further
operable to cause the processor to: receive an UL grant for a
subsequent time period; and resume transmission in the managed RF
spectrum band during the subsequent time period based at least in
part on the UL grant.
39. An apparatus for wireless communication, comprising: a
processor; memory in electronic communication with the processor;
and instructions stored in the memory and operable, when executed
by the processor, to cause the apparatus to: receive, from a
wireless device, a silencing signal in a managed radio frequency
(RF) spectrum band indicating that at least one neighboring user
equipment (UE) is to suspend uplink (UL) transmission in the
managed RF spectrum band, wherein the silencing signal is based at
least in part on a determination that a clear channel assessment
(CCA) has failed, and wherein a first radio access technology (RAT)
operating in the managed RF spectrum band is synchronized with a
second RAT operating in a shared RF spectrum band; and switch from
receiving transmissions in the shared RF spectrum band by the
wireless device to receiving transmissions in the managed RF
spectrum band by the wireless device, wherein the wireless device
is a source of the silencing signal and the switching is based at
least in part on the silencing signal.
40. The apparatus of claim 39, wherein the instructions are further
operable to cause the processor to: power up a radio for the
managed RF spectrum band; and listen, using the radio, for the
silencing signal in the managed RF spectrum band during a first
portion of a subframe of a radio frame structure.
41. A non-transitory computer-readable medium storing code for
wireless communication, the code comprising instructions executable
to: determine a clear channel assessment (CCA) in a shared radio
frequency (RF) spectrum band has failed, wherein a radio access
technology (RAT) operating in the shared RF spectrum band is
synchronized with a RAT operating in a managed RF spectrum band;
transmit a silencing signal in the managed RF spectrum band
indicating that at least one neighboring user equipment (UE) is to
suspend uplink (UL) transmission in the managed RF spectrum band,
wherein transmitting the silencing signal is based at least in part
on the determination; and transmit a message in the managed RF
spectrum band based at least in part on the silencing signal.
42. A non-transitory computer-readable medium storing code for
wireless communication, the code comprising instructions executable
to: identify resources for an uplink (UL) transmission associated
with a first radio access technology (RAT) operating in a managed
radio frequency (RF) spectrum band, wherein the first RAT operating
in the managed RF spectrum band is synchronized with a second RAT
operating in a shared RF spectrum band; receive, from a wireless
device, a silencing signal in the managed RF spectrum band
indicating that at least one neighboring user equipment (UE) is to
suspend UL transmission in the managed RF spectrum band, wherein
receiving the silencing signal is during a time period including
the identified resources, and wherein the silencing signal is based
at least in part on a determination that a clear channel assessment
(CCA) has failed; and suspend transmission in the managed RF
spectrum band during the time period based at least in part on the
silencing signal.
43. A non-transitory computer-readable medium storing code for
wireless communication, the code comprising instructions executable
to: receive, from a wireless device, a silencing signal in a
managed radio frequency (RF) spectrum band indicating that at least
one neighboring user equipment (UE) is to suspend uplink (UL)
transmission in the managed RF spectrum band, wherein the silencing
signal is based at least in part on a determination that a clear
channel assessment (CCA) has failed, and wherein a first radio
access technology (RAT) operating in the managed RF spectrum band
is synchronized with a second RAT operating in a shared RF spectrum
band; and switch from receiving transmissions in the shared RF
spectrum band by the wireless device to receiving transmissions in
the managed RF spectrum band by the wireless device, wherein the
wireless device is a source of the silencing signal and the
switching is based at least in part on the silencing signal.
44. The method of claim 1, wherein at least a portion the silencing
signal is transmitted during a period of time during which a base
station transmits downlink (DL) control signaling.
Description
BACKGROUND
The following relates generally to wireless communication, and more
specifically to user equipment (UE) silencing based on clear
channel assessment (CCA) in shared or unlicensed spectrum.
Wireless communications systems are widely deployed to provide
various types of communication content such as voice, video, packet
data, messaging, broadcast, and so on. These systems may be capable
of supporting communication with multiple users by sharing the
available system resources (e.g., time, frequency, and power).
Examples of such multiple-access systems include code division
multiple access (CDMA) systems, time division multiple access
(TDMA) systems, frequency division multiple access (FDMA) systems,
and orthogonal frequency division multiple access (OFDMA) systems.
A wireless multiple-access communications system may include a
number of base stations, each simultaneously supporting
communication for multiple communication devices, which may be
otherwise known as UEs.
In some cases, wireless devices may communicate critical or latency
sensitive information in a shared radio frequency (RF) spectrum
band. However, communications in a shared band may be subject to
contention based access procedures that prevent a device from
accessing a channel. This may result in disruptions to critical
signaling between wireless devices, such as control signaling.
SUMMARY
A wireless device communicating critical or latency sensitive
information may determine that a clear channel assessment (CCA) has
failed in a shared radio frequency (RF) spectrum band (e.g., an RF
spectrum band shared by a number of different licensees, a shared
RF spectrum band, or other RF spectrum in which a wireless device
contends for access with other wireless devices). The device may
then transmit a silencing signal in a managed RF spectrum band
(e.g., a licensed RF spectrum band), and switch to communicating in
the managed band from transmitting in the shared band. Other
wireless devices communicating with the first device may receive
the silencing signal and may also switch to the managed RF spectrum
band. Based on the silencing signal, user equipments (UEs) not
associated with the critical communications, but also operating in
the managed band, may suspend transmissions in the managed band
(e.g., uplink (UL) data), although they may still receive
transmissions in the managed band (e.g., downlink (DL) data).
A method of wireless communication is described. The method may
include determining that a CCA in a shared RF spectrum band has
failed, a radio access technology (RAT) operating in the shared RF
spectrum band is synchronized with a RAT operating in a managed RF
spectrum band, transmitting a silencing signal in the managed RF
spectrum band based at least in part on the determination and
transmitting a message in the managed RF spectrum band based at
least in part on the silencing signal.
An apparatus for wireless communication is described. The apparatus
may include means for determining that a CCA in a shared RF
spectrum band has failed, a RAT operating in the shared RF spectrum
band is synchronized with a RAT operating in a managed RF spectrum
band, means for transmitting a silencing signal in the managed RF
spectrum band based at least in part on the determination and means
for transmitting a message in the managed RF spectrum band based at
least in part on the silencing signal.
A further apparatus is described. The apparatus may include a
processor, memory in electronic communication with the processor,
and instructions stored in the memory. The instructions may be
operable to cause the processor to determine that a CCA in a shared
RF spectrum band has failed, a RAT operating in the shared RF
spectrum band is synchronized with a RAT operating in a managed RF
spectrum band, transmit a silencing signal in the managed RF
spectrum band based at least in part on the determination and
transmit a message in the managed RF spectrum band based at least
in part on the silencing signal.
A non-transitory computer-readable medium for wireless
communication is described. The non-transitory computer-readable
medium may include instructions to cause a processor to determine
that a CCA in a shared RF spectrum band has failed, where a RAT
operating in the shared RF spectrum band is synchronized with a RAT
operating in a managed RF spectrum band, transmit a silencing
signal in the managed RF spectrum band based on the determination
and transmit a message in the managed RF spectrum band based on the
silencing signal.
Some examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for determining that a
subsequent CCA in the shared RF spectrum band has succeeded after
the CCA. Some examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for transmitting a
subsequent message in the shared RF spectrum band based on the
determination that the subsequent CCA has succeeded.
Some examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for determining that a
subsequent CCA in the shared RF spectrum band has failed after the
CCA. Some examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for transmitting a
subsequent silencing signal in the managed RF spectrum band based
on the determination that the subsequent CCA has failed. Some
examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for transmitting a
subsequent message in the shared RF spectrum band based on the
subsequent silencing signal.
Some examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for performing the CCA
in a time slot prior to a first subframe of a radio frame, where
the message is transmitted in the first subframe.
In some examples of the method, apparatus, or non-transitory
computer-readable medium described above, transmitting the
silencing signal in the managed RF spectrum band includes
transmitting the silencing signal during a first time slot of a
subframe of a radio frame structure of the managed RF spectrum band
based on the determination.
In some examples of the method, apparatus, or non-transitory
computer-readable medium described above, the silencing signal
includes a multi-tone orthogonal frequency division multiplexing
(OFDM) signal, a pseudo-noise (PN) signal, or a constant amplitude
zero autocorrelation (CAZAC) signal.
In some examples of the method, apparatus, or non-transitory
computer-readable medium described above, the message includes
information for a mission critical application or for a control
application.
In some examples of the method, apparatus, or non-transitory
computer-readable medium described above, the managed RF spectrum
band includes a portion of a system bandwidth of a wireless wide
area network (WWAN).
In some examples of the method, apparatus, or non-transitory
computer-readable medium described above, the time resources of the
managed RF spectrum band are organized according to a time division
duplex (TDD) configuration.
A method of wireless communication is described. The method may
include identifying resources for an UL transmission associated
with a RAT operating in a managed RF spectrum band, receiving a
silencing signal in the managed RF spectrum band during a time
period including the identified resources, the silencing signal is
based at least in part on a determination that a CCA has failed,
and a second RAT operating in a shared RF spectrum band is
synchronized with the first RAT operating in the managed RF
spectrum band and suspending transmission in the managed RF
spectrum band during the time period based at least in part on the
silencing signal.
An apparatus for wireless communication is described. The apparatus
may include means for identifying resources for an UL transmission
associated with a RAT operating in a managed RF spectrum band,
means for receiving a silencing signal in the managed RF spectrum
band during a time period including the identified resources, the
silencing signal is based at least in part on a determination that
a CCA has failed, and a second RAT operating in a shared RF
spectrum band is synchronized with the first RAT operating in the
managed RF spectrum band and means for suspending transmission in
the managed RF spectrum band during the time period based at least
in part on the silencing signal.
A further apparatus is described. The apparatus may include a
processor, memory in electronic communication with the processor,
and instructions stored in the memory. The instructions may be
operable to cause the processor to identify resources for an UL
transmission associated with a RAT operating in a managed RF
spectrum band, receive a silencing signal in the managed RF
spectrum band during a time period including the identified
resources, the silencing signal is based at least in part on a
determination that a CCA has failed, and a second RAT operating in
a shared RF spectrum band is synchronized with the first RAT
operating in the managed RF spectrum band and suspend transmission
in the managed RF spectrum band during the time period based at
least in part on the silencing signal.
A non-transitory computer-readable medium for wireless
communication is described. The non-transitory computer-readable
medium may include instructions to cause a processor to identify
resources for an UL transmission associated with a RAT operating in
a managed RF spectrum band, receive a silencing signal in the
managed RF spectrum band during a time period including the
identified resources, where the silencing signal is based on a
determination that a CCA has failed, and where a second RAT
operating in a shared RF spectrum band is synchronized with the
first RAT operating in the managed RF spectrum band and suspend
transmission in the managed RF spectrum band during the time period
based on the silencing signal.
Some examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for receiving an UL
grant, where the resources are identified based on the UL
grant.
Some examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for receiving a DL
transmission during the time period based on the DL grant.
Some examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for receiving an UL
grant for a subsequent time period. Some examples of the method,
apparatus, or non-transitory computer-readable medium described
above may further include processes, features, means, or
instructions for resuming transmission in the managed RF spectrum
band during the subsequent time period based on the UL grant.
A method of wireless communication is described. The method may
include receiving a silencing signal in a managed RF spectrum band,
the silencing signal is based at least in part on a determination
that a CCA has failed, and a first RAT operating in the managed RF
spectrum band is synchronized with a second RAT operating in a
shared RF spectrum band and switching from receiving transmissions
from a source of the silencing signal in the shared RF spectrum
band to receiving transmissions from the source of the silencing
signal in the managed RF spectrum band based at least in part on
the silencing signal.
An apparatus for wireless communication is described. The apparatus
may include means for receiving a silencing signal in a managed RF
spectrum band, the silencing signal is based at least in part on a
determination that a CCA has failed, and a first RAT operating in
the managed RF spectrum band is synchronized with a second RAT
operating in a shared RF spectrum band and means for switching from
receiving transmissions from a source of the silencing signal in
the shared RF spectrum band to receiving transmissions from the
source of the silencing signal in the managed RF spectrum band
based at least in part on the silencing signal.
A further apparatus is described. The apparatus may include a
processor, memory in electronic communication with the processor,
and instructions stored in the memory. The instructions may be
operable to cause the processor to receive a silencing signal in a
managed RF spectrum band, the silencing signal is based at least in
part on a determination that a CCA has failed, and a first RAT
operating in the managed RF spectrum band is synchronized with a
second RAT operating in a shared RF spectrum band and switch from
receiving transmissions from a source of the silencing signal in
the shared RF spectrum band to receiving transmissions from the
source of the silencing signal in the managed RF spectrum band
based at least in part on the silencing signal.
A non-transitory computer-readable medium for wireless
communication is described. The non-transitory computer-readable
medium may include instructions to cause a processor to receive a
silencing signal in a managed RF spectrum band, where the silencing
signal is based on a determination that a CCA has failed, and where
a first RAT operating in the managed RF spectrum band is
synchronized with a second RAT operating in a shared RF spectrum
band and switch from receiving transmissions from a source of the
silencing signal in the shared RF spectrum band to receiving
transmissions from the source of the silencing signal in the
managed RF spectrum band based on the silencing signal.
Some examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for powering up a radio
for the managed RF spectrum band. Some examples of the method,
apparatus, or non-transitory computer-readable medium described
above may further include processes, features, means, or
instructions for listening, using the radio, for the silencing
signal in the managed RF spectrum band during a first portion of a
subframe of a radio frame structure.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates an example of a wireless communications system
that supports user equipment (UE) silencing based on clear channel
assessment (CCA) in shared spectrum in accordance with aspects of
the present disclosure;
FIG. 2 illustrates an example of a wireless communications system
that supports UE silencing based on CCA in shared spectrum in
accordance with aspects of the present disclosure;
FIG. 3 illustrates an example of a timing diagram that illustrates
UE silencing based on CCA in shared spectrum in accordance with
aspects of the present disclosure;
FIG. 4 illustrates an example of a process flow in a system that
supports UE silencing based on CCA in shared spectrum in accordance
with aspects of the present disclosure;
FIGS. 5 through 7 show block diagrams of wireless devices that
support UE silencing based on CCA in shared spectrum in accordance
with aspects of the present disclosure;
FIG. 8 illustrates a block diagram of a system including a UE that
supports UE silencing based on CCA in shared spectrum in accordance
with aspects of the present disclosure;
FIGS. 9 through 11 show block diagrams of wireless devices that
support UE silencing based on CCA in shared spectrum in accordance
with aspects of the present disclosure;
FIG. 12 illustrates a block diagram of a system including a UE that
supports UE silencing based on CCA in shared spectrum in accordance
with aspects of the present disclosure; and
FIGS. 13 through 15 illustrate methods for UE silencing based on
CCA in shared spectrum in accordance with aspects of the present
disclosure.
DETAILED DESCRIPTION
Shared radio frequency (RF) spectrum may offer a large amount of
bandwidth for a particular application to meet a high capacity
demand at low cost. A shared RF spectrum band may include an
unlicensed RF spectrum band (or "unlicensed band"), an RF spectrum
band for which multiple licensees have the right to access the
spectrum, or other RF spectrum bands for which wireless devices
contend for access. However, traffic in a shared RF spectrum band
(or "shared band") may be subject to interference from other
systems operating in the same shared band. Such interference may be
detrimental to an application that has low packet error rate or
latency tolerance. For example, wireless devices engaged in a
mission-critical application that communicate using a shared band
may be subject to interference from other wireless devices
operating in the same band that are nearby. Transmissions may fail
due to this interference. Managed RF spectrum bands (or "managed
bands) may include licensed RF spectrum bands, such as RF spectrum
bands administered by a regulator that has provided a license for
an operator to provide services that use the RF spectrum band and
are centrally managed by the operator. Using a managed RF spectrum
band provided by an operator for the application rather than a
shared band may address packet error rates or latencies associated
with using the shared band, but may be uneconomical for the
particular application.
In a mission-critical application, a wireless device may use a
shared band for an initial sequence of transmissions of a packet.
Based on a listen-before-talk (LBT) procedure such as a clear
channel assessment (CCA), the device may determine that the shared
channel is not available. The device may then switch to
communicating in a managed band. In order to reduce interference
from user equipments (UEs) operating in managed spectrum, the
transmitter may send a silencing signal at the beginning of the
subframe, which may align with a time slot associated with a base
station control channel. If the UEs receive and decode the
silencing signal they may suspend uplink (UL) transmissions for the
duration of the subframe.
To facilitate switching to a managed band, mission-critical traffic
may operate using a mutually synchronized subframe structure with
cellular traffic of a cellular network operating in managed
spectrum. That is, wireless devices operating in shared spectrum
may synchronize their operations with a wide area network (WAN)
that operates in managed spectrum. This may allow the wireless
devices operating in shared spectrum to switch to managed spectrum
without disruption of the timing of mission-critical
communications.
Aspects of the disclosure are initially described in the context of
a wireless communication system. Examples are then described in
which a wireless device performs a CCA, transmits a silencing
signal, and switches to managed spectrum. Aspects of the disclosure
are further illustrated by and described with reference to
apparatus diagrams, system diagrams, and flowcharts that relate to
UE silencing based on CCA in shared spectrum.
FIG. 1 illustrates an example of a wireless communications system
100 that supports UE silencing based on CCA in shared spectrum in
accordance with various aspects of the present disclosure. The
wireless communications system 100 includes base stations 105, UEs
115, and a core network 130. In some examples, the wireless
communications system 100 may include a Long Term Evolution
(LTE)/LTE-Advanced (LTE-A) network. Wireless communications system
100 may support a local network of wireless devices 135 that may
switch from a shared to a managed RF spectrum band if a CCA failure
is detected.
For example, a first wireless device 135 operating in the wireless
communications system 100 may transmit on a shared RF spectrum band
to one or more other wireless devices 135. Prior to transmission,
the first wireless device may perform a CCA (e.g., prior to the
start of a subframe). If the shared channel is busy, the first
wireless device 135 may transmit a silencing signal on a managed
band. UEs 115 that receive the silencing signal may refrain from UL
transmissions during the subframe in which the silencing signal was
sent, and the first wireless device 135 may transmit to the one or
more wireless devices 135 using the managed band during the
subframe. A subframe may refer to a division of a frame of the
wireless communication system 100. A frame may refer to a discrete
set of physical resources that may be used to communicate data
using the wireless communication system 100. A frame may include
both time domain resources and frequency domain resources. For
example, the duration of one LTE radio frame may be 10 ms. One
frame may be divided into 10 subframes of 1 ms each, and each
subframe may be divided into two slots of 0.5 ms each. Each slot
may contain six or seven OFDM symbols, depending on a cyclic prefix
(CP) length. In an LTE communication network, scheduling of
physical resources may, in some examples, be done on a subframe by
subframe basis, and be for uplink and/or downlink data.
In some cases, wireless devices may switch from operating using a
first radio access technology (RAT) when operating in the shared
band to using a second RAT when operating in the managed band. For
example, the first RAT may use a contention based access procedure.
In some cases, the first RAT and the second RAT may be the same
RAT, or different versions or releases of the same RAT. Also, the
one or more RATs used by wireless devices 135 may be the same or
different from a RAT used by UEs 115 and base station 105. In some
cases, the managed band may be a licensed RF spectrum band such
that the second RAT may use a scheduled access procedure to access
the licensed RF spectrum band for communication.
Base stations 105 may wirelessly communicate with UEs 115 via one
or more base station antennas. Each base station 105 may provide
communication coverage for a respective geographic coverage area
110. Communication links 125 shown in wireless communications
system 100 may include UL transmissions from a UE 115 to a base
station 105, or DL transmissions, from a base station 105 to a UE
115. UEs 115 may be dispersed throughout the wireless
communications system 100, and each UE 115 may be stationary or
mobile. A UE 115 may also be referred to as a mobile station, a
subscriber station, a remote unit, a wireless device, an access
terminal (AT), a handset, a user agent, a client, or like
terminology. A UE 115 may also be a cellular phone, a wireless
modem, a handheld device, a personal computer, a tablet, a personal
electronic device, an machine type communication (MTC) device,
etc.
Base stations 105 may communicate with the core network 130 and
with one another. For example, base stations 105 may interface with
the core network 130 through backhaul links 132 (e.g., S1, etc.).
Base stations 105 may communicate with one another over backhaul
links 134 (e.g., X2, etc.) either directly or indirectly (e.g.,
through core network 130). Base stations 105 may perform radio
configuration and scheduling for communication with UEs 115, or may
operate under the control of a base station controller (not shown).
In some examples, base stations 105 may be macro cells, small
cells, hot spots, or the like. Base stations 105 may also be
referred to as eNodeBs (eNBs) 105. UEs 115 may include a UE
communication silencing manager 116, which may identify resources
for an UL transmission associated with a first RAT operating in a
managed RF spectrum band, receive a silencing signal in the managed
RF spectrum band for a time period including the identified
resources, where the silencing signal is based on a determination
that a transmission in a shared RF spectrum band has failed, and
where a second RAT operating in the shared RF spectrum band is
synchronized with the first RAT operating in the managed RF
spectrum band, and suspend transmission in the managed RF spectrum
band during the time period based on the silencing signal. The UE
communication silencing manager 116 may also be an example of
aspects of the UE communication silencing manager 1205 described
with reference to FIG. 12.
Wireless communications system 100 may include a network of
wireless devices 135 that operate in coverage area 111 using
communication links 126. For example, wireless devices 135 may be
controllers, sensors, or actuators within a factory automation
network. In other examples, wireless devices may be a part of a
home automation network, or an internet of things (JOT)
network.
Wireless devices 135 may include CCA based silencing manager 136,
which may determine that a CCA a shared RF spectrum band has
failed, transmit a silencing signal in an managed RF spectrum band
based on the determination, and communicate in the managed RF
spectrum band based on the silencing signal. The CCA based
silencing manager 136 may also receive a silencing signal in a
managed RF spectrum band, and switch from communicating with a
source of the silencing signal in the shared RF spectrum band to
communicating with the source of the silencing signal in the
managed RF spectrum band based on the silencing signal. The CCA
based silencing manager 136 may also be an example of aspects of
the CCA based silencing manager 805 described with reference to
FIG. 8.
A wireless device 135, UE 115, or base station 105 may operate in a
shared or shared frequency spectrum. These devices may perform a
CCA prior to communicating in order to determine whether the
channel is available. A CCA may include an energy detection
procedure to determine whether there are any other active
transmissions. For example, the device may infer that a change in a
received signal strength indication (RSSI) of a power meter
indicates that a channel is occupied. Specifically, signal power is
that is concentrated in a certain bandwidth and exceeds a
predetermined noise floor may indicate another wireless transmitter
that may result in an indication that the CCA has failed. A CCA may
also include detection of specific sequences that indicate use of
the channel. For example, another device may transmit a specific
preamble prior to transmitting a data sequence. Thus, if a CCA
indicates that a channel is being used by another transmitting
device, the CCA may be determined to have failed.
In some cases, transmission failure and retransmission may be
determined based on a hybrid automatic repeat request (HARQ)
procedure. HARQ may be a method of ensuring that data is received
correctly over a wireless communication link 125. HARQ may include
a combination of error detection (e.g., using a CRC), forward error
correction (FEC), and retransmission (e.g., automatic repeat
request (ARQ)). HARQ may improve throughput at the medium access
control (MAC) layer in poor radio conditions (e.g., signal-to-noise
conditions). In Incremental Redundancy HARQ, incorrectly received
data may be stored in a buffer and combined with subsequent
transmissions to improve the overall likelihood of successfully
decoding the data. In some cases, redundancy bits are added to each
message prior to transmission. This may be useful in poor
conditions. In other cases, redundancy bits are not added to each
transmission, but are retransmitted after the transmitter of the
original message receives a NACK indicating a failed attempt to
decode the information. The chain of transmission, response and
retransmission may be referred to as a HARQ process. In some cases,
a limited number of HARQ processes may be used for a given
communication link 125.
In some cases, wireless communications system 100 may utilize one
or more enhanced component carrier (eCC)s. An eCC may be
characterized by one or more features including flexible bandwidth,
different transmission time interval (TTI)s, and modified control
channel configuration. In some cases, an eCC may be associated with
a carrier aggregation (CA) configuration or a dual connectivity
configuration (e.g., when multiple serving cells have a suboptimal
backhaul link). An eCC may also be configured for use in unlicensed
spectrum or other shared spectrum (e.g., where more than one
operator is licensed to use the spectrum).
An eCC characterized by flexible bandwidth may include one or more
segments that may be utilized by UEs 115 that do are not capable of
monitoring the whole bandwidth or prefer to use a limited bandwidth
(e.g., to conserve power). In some cases, an eCC may utilize a
different TTI length than other component carriers (CCs), which may
include use of a reduced or variable symbol duration as compared
with TTIs of the other CCs. The symbol duration may remain the
same, in some cases, but each symbol may represent a distinct TTI.
In some examples, an eCC may support transmissions using different
TTI lengths. For example, some CCs may use uniform 1 ms TTIs,
whereas an eCC may use a TTI length of a single symbol, a pair of
symbols, or a slot. In some cases, a shorter symbol duration may
also be associated with increased subcarrier spacing. In
conjunction with the reduced TTI length, an eCC may utilize dynamic
TDD operation (e.g., it may switch from DL to UL operation for
short bursts according to dynamic conditions.)
Flexible bandwidth and variable TTIs may be associated with a
modified control channel configuration (e.g., an eCC may utilize an
enhanced physical downlink control channel (ePDCCH) for DL control
information). For example, one or more control channels of an eCC
may utilize frequency-division multiplexing (FDM) scheduling to
accommodate flexible bandwidth use. Other control channel
modifications include the use of additional control channels (e.g.,
for evolved multimedia broadcast multicast service (eMBMS)
scheduling, or to indicate the length of variable length UL and DL
bursts), or control channels transmitted at different intervals. An
eCC may also include modified or additional hybrid automatic repeat
request (HARM) related control information.
Accordingly, a wireless device 135 communicating critical or
latency sensitive information may determine that a CCA has failed
in a shared RF spectrum band. The device may then transmit a
silencing signal in a managed RF spectrum band, and switch to
communicating in the managed band. Other wireless devices
communicating with the first device may receive the silencing
signal and may also switch to the managed RF spectrum band. Based
on the silencing signal, UEs 115 not associated with the critical
communications and operating in the managed band may suspend
transmissions, although they may still receive DL data.
FIG. 2 illustrates an example of a wireless communications system
200 that supports UE silencing based on CCA in shared spectrum in
accordance with various aspects of the present disclosure. Wireless
communications system 200 may include base station 105-a and UE
115-a, which may be examples of the corresponding devices described
with reference to FIG. 1. Wireless communications system 200 may
support a local network of wireless devices 135 that may switch
from a shared to a managed RF spectrum band if a CCA failure is
detected. In some cases, the local network may support
mission-critical or latency-sensitive information (such as control
information for a closed loop control system as in a factory
automation or home automation network). The local network may also
be referred to as a mission-critical network or a critical
information network.
In some cases, wireless device 135-a may transmit mission-critical
(e.g., latency sensitive) information via a wireless link 205 to
wireless devices 135-b in a shared RF spectrum band using a first
RAT. Base station 105-a may communicate with UE 115-a via wireless
link 210 using a second RAT in managed RF spectrum, which may
potentially cause interference 215 with communications of the
wireless devices 135 (e.g., if wireless devices 135 and UE 115-a
were to transmit on the same frequency at the same time).
Operations using the first RAT may be synchronized to operations
using the second RAT. That is communication in a shared band may be
synchronized to operations, including communications, in a managed
band used by base station 105-a and UE 115-a.
In some cases, wireless device 135-a that uses the first RAT may
perform CCA before transmitting to wireless device 135-b, wireless
device 135-c, wireless device 135-d, or another wireless device 135
in a local network (e.g., a factory or home automation network). If
the channel on the shared band is busy, wireless device 135-a may
transmit to wireless device 135-b in the managed band instead of
the shared band. When transmitting on the managed band, wireless
device 135-a may use a second RAT. In some cases, the second RAT
may be the same as the first RAT.
Prior to transmitting in the managed RF spectrum band supporting a
radio frame structure, wireless device 135-a may transmit a
silencing signal at the beginning of a subframe, for example in the
first slot of the subframe during which the wireless device 135-a
will transmit a message. The silencing signal may occur during the
same time period as a physical downlink control channel (PDCCH)
signal of base station 105-a. Neighboring wireless devices on the
managed RF spectrum band, such as UE 115-a, may attempt to decode
both the PDCCH signal and the silencing signal. In some cases, the
second RAT used by wireless device 135-a may be the same as a RAT
being used by UE 115-a, or it may be different.
If UE 115-a, operating on the managed band, identifies the
silencing signal, it may suspend UL transmission for the duration
of the subframe. By suspending transmission for the subframe, UE
115-a may reduce possible interference for wireless device 135-a.
If UE 115-a does not receive the silencing signal, or otherwise
does not decode the silencing signal, UE 115-a may continue with UL
transmission. If UE 115-a refrains from UL transmission, UE 115-a
may continue to receive DL information from base station 105-a.
After transmitting for the subframe on the managed cellular
network, wireless device 135-a may then continue to transmit on the
shared network. In this example, a frame may be an example of a
TTI, a time slot, or a subframe.
In one example, a wireless system may utilize TDD-based resource
partitioning of both a shared RF spectrum band and a managed RF
spectrum band. In this example, the information being transmitted
may be mission-critical (e.g., latency sensitive), and therefore
interference of the information may lead to detrimental effects of
a system.
In some cases, the wireless network may be a factory automation
network, where the system being controlled by the factory
automation network may be, for example, a production line. The
wireless network may utilize a mutually synchronized frame
structure for the managed RF spectrum band and the shared RF
spectrum band, which may be further synchronized with cellular
traffic. However, the cellular network may support extended links,
for example from UE 115-a within the range of the factory
automation network to base station 105-a outside the range of the
factory automation network.
If wireless device 135-a determines that a channel in the shared
band is busy, wireless device 135-a may transmit its information,
which may be mission-critical, in the managed band. In some cases,
to reduce further transmission interference, it may be appropriate
to silence neighboring devices operating in the managed band.
However, it may be appropriate for only the managed RF spectrum
band transmissions within the vicinity of the critical information
network to be silenced, for example by determining a threshold at
which transmission interference may cause signal loss. For network
infrastructure nodes supporting the cellular traffic, such as base
station 105-a, this may be achieved by keeping sufficient distance
between base station 105-a and wireless device 135-a. However, for
a wireless device on the managed RF spectrum band, for example UE
115-a, wireless device 135-a may transmit an Over-The-Air silencing
signal in the managed spectrum prior to using the managed spectrum
for mission-critical traffic. In this example of a cellular TDD
system, the silencing signal may be transmitted during time slots
where UE 115-a may expect DL traffic. This may allow UE 115-a to
receive and decode the silencing signal.
If UE 115-a decodes the silencing signal, UE 115-a may suspend
transmission for a predefined time interval, for example a time
slot, subframe, or a TTI, which may last for as long as wireless
device 135-a utilizes the shared RF spectrum band. During the
silenced period, wireless device 135-a may transmit on the managed
RF spectrum band uninterrupted (e.g., by interference 215). In some
cases, interference 215 from base station 105-a may not be as
significant as that from UE 115-a, for example because UE 115-a is
located closer to the wireless devices 135.
In some cases, base station 105-a may interpret silence of UE 115-a
as an outage, which may be handled by ARQ or HARQ mechanisms. If
base station 105-a engages in transmissions during the silenced
time interval, UE 115-a may receive the DL communications. However,
in some cases, UE 115-a may not be able to receive a signal of base
station 105-a signal due to being over-powered by the
mission-critical traffic. If so, a missed signal from base station
105-a may also be corrected by existing ARQ or HARQ mechanisms.
The critical information network and the cellular network may use a
mutually synchronized frame structure. For example, the critical
information network may be synchronized to the cellular network to
facilitate switching from the shared band to the managed band.
Synchronization of the two networks may cause the decoding of a
transmitted silencing signal to be reduced to short, periodic time
slots. Furthermore, suspension of uplink cellular traffic may be
limited to the time interval used by the critical information
network in the managed band.
FIG. 3 illustrates an example of timing diagram 300 for UE
silencing based on CCA in shared spectrum in accordance with
various aspects of the present disclosure. In some cases, UE
transmission suspension in managed band 310 may represent aspects
of techniques performed by a UE 115, base station 105, or wireless
device 135 as described with reference to FIGS. 1 through 2.
Wireless device 135-e and wireless device 135-f may be operating in
a shared band 305 for mission-critical transmission. UE 115-b may
operate on the managed band 310 and communicate with base station
105-b (which may be located far away from the critical information
network). Before wireless device 135-e transmits to wireless device
135-f, wireless device 135-e may perform CCA 315-a in a dedicated
time slot prior to subframe 325-a where data are to be sent. If the
channel is idle, wireless device 135-e may send transmission 320-a
in the following time slot in the shared band 305. However, if CCA
315-b indicates that the shared band 305 is busy, wireless device
135-e may transmit a silencing signal 335 in the managed band 310
at the beginning of a subsequent subframe 325-c, followed by
transmission 320-b (also in the managed band 310).
UE 115-b may transmit and receive during unrestricted time period
340 in the managed band 310. However, UE 115-b may also listen for
control information and silencing signal 335 at the start of each
subframe 325. If UE 115-b identifies silencing signal 335, UE 115-b
may suspend UL transmissions for the remainder of subframe 325-c
during restricted time period 350. UE 115-c may still receive DL
control message 345 from base station 105-b for the duration of
subframe 325-c. During other times, UE 115-b may conduct UL or DL
traffic with base station 105-b. Suspending a transmission of UE
115-b in subframe 325-c may allow wireless device 135-e to transmit
in managed band 310 without interference.
Silencing signal 335 may be transmitted at the beginning of each
subframe 325 during a period used by base station 105-b for DL
control message 345. All of subframe 325 may be utilized by
cellular traffic in the absence of mission-critical traffic.
The silencing signal 335 may include one or more bits of
information. The silencing signal 335 may be spread over a portion
or all of the managed band 310. Using a large band for the
silencing signal 335 may lower a detection threshold of UE 115-b
due to the processing gain associated with spreading, which may
make the operation of mission-critical traffic more robust. In some
cases, the silencing signal comprises a multi-tone orthogonal
frequency division multiplexing (OFDM) signal, a pseudo-noise (PN)
signal, or a constant amplitude zero autocorrelation (CAZAC)
signal. The signal may represent a single bit of information, or
ins some cases, may include more than one bit.
The silencing signal 335 may also be received by wireless device
135-f. In some cases, wireless device 135-f may treat the reception
of the silencing signal 335 as an indicator to use the managed band
310 for reception. In some cases, if wireless device 135-f does not
receive the silencing signal 335, wireless device 135-f may power
down a radio in managed band 310 for the remainder of the subframe
325, which may conserve power.
In some cases, wireless device 135-f may be scheduled for a traffic
burst in one of the subframes 325. Wireless device 135-f may
respond to a transmission, which wireless device 135-f may have
received from wireless device 135-e. In some cases, the response
from wireless device 135-f may occur in the same subframe 325,
without wireless device 135-f performing CCA. In this case, the
transmission may still be protected by the clearance of UE 115-b
traffic for all of subframe 325. In some cases, wireless device
135-e may communicate at the same time with multiple correspondents
in each subframe 325 using multiplexing methods such as frequency
division or code division multiplexing.
Some aspects of this disclosure may be applied to cellular TDD
systems where the silencing signal falls on a time slot used by a
base station 105 to transmit a control signal such as a PDCCH. Some
aspects of this disclosure may be applied to cellular FDD systems
where a UE 115 uses a managed band for device-to-device (D2D)
communications, in addition to conducting UL traffic to the
network.
FIG. 4 illustrates an example of a process flow 400 for UE
silencing based on CCA in shared spectrum in accordance with
various aspects of the present disclosure. Process flow 400 may
include wireless devices 135-g and 135-h, as well as UE 115-a,
which may be examples of the corresponding devices described with
reference to FIG. 1 through 3.
At step 405, wireless device 135-g may communicate with wireless
device 135-h in a shared band. Wireless device 135-g may perform a
CCA in the shared band prior to communicating and may have
determined that the shared RF spectrum band is available. Wireless
device 135-g may also communicate with additional wireless devices
135 (not shown). In some cases, the communication between wireless
devices 135 is mission-critical communication such as closed loop
control communications in a factory or home automation network.
At step 410, wireless device 135-g may perform a CCA before
transmitting to wireless device 135-h during a subsequent subframe.
If the CCA fails, for example by determining that the channel is
busy at step 415, wireless device 135-g may transmit on a managed
RF spectrum band instead of the shared RF spectrum band.
Prior to transmitting on a managed band, wireless device 135-g may
transmit a silencing signal to neighboring wireless devices 135 and
UEs 115 at step 420. The silencing signal may be received and
decoded by wireless device 135-h and UE 115-c. In some cases, the
silencing signal comprises a multi-tone OFDM signal, a PN signal,
or a CAZAC signal. The signal may represent a single bit of
information, or in some cases, may include more than one bit.
Upon receiving the silencing signal, UE 115-c may suspend UL
transmissions at step 425. Suspension of transmissions from UE
115-c in the managed band may reduce possible interference for
wireless device 135-g. Wireless device 135-g may then transmit to
wireless device 135-h on the managed RF spectrum band.
FIG. 5 shows a block diagram of a wireless device 500 that supports
UE silencing based on CCA in shared spectrum in accordance with
various aspects of the present disclosure. Wireless device 500 may
be an example of aspects of a wireless device 135 described with
reference to FIGS. 1 through 4. Wireless device 500 may include
receiver 505, CCA based silencing manager 510 and transmitter 515.
Wireless device 500 may also include a processor and memory. Each
of these components may be in communication with each other.
The receiver 505 may receive information such as packets, user
data, or control information associated with various information
channels (e.g., control channels, data channels, information
related to UE silencing based on CCA in shared spectrum, etc.).
Information may be passed on to other components of the wireless
device 500. The receiver 505 may be an example of aspects of the
transceiver 825 described with reference to FIG. 8.
The CCA based silencing manager 510 may determine that a CCA in a
shared RF spectrum band has failed, where a RAT operating in the
shared RF spectrum band is synchronized with a RAT operating in a
managed RF spectrum band, transmit a silencing signal in the
managed RF spectrum band based on the determination, and transmit a
message in the managed RF spectrum band based on the silencing
signal. The CCA based silencing manager 510 may also be an example
of aspects of the CCA based silencing manager 805 described with
reference to FIG. 8.
The CCA based silencing manager 510 may also receive a silencing
signal in a managed RF spectrum band, where the silencing signal is
based on a determination that a CCA has failed, and where a first
RAT operating in the managed RF spectrum band is synchronized with
a second RAT operating in a shared RF spectrum band, and switch
from receiving transmissions from a source of the silencing signal
in the shared RF spectrum band to receiving transmissions from the
source of the silencing signal in the managed RF spectrum band
based on the silencing signal.
The transmitter 515 may transmit signals received from other
components of wireless device 500. In some examples, the
transmitter 515 may be collocated with a receiver in a transceiver
module. For example, the transmitter 515 may be an example of
aspects of the transceiver 825 described with reference to FIG. 8.
The transmitter 515 may include a single antenna, or it may include
a plurality of antennas.
FIG. 6 shows a block diagram of a wireless device 600 that supports
UE silencing based on CCA in shared spectrum in accordance with
various aspects of the present disclosure. Wireless device 600 may
be an example of aspects of a wireless device 500 or a wireless
device 135 described with reference to FIGS. 1-5. Wireless device
600 may include receiver 605, CCA based silencing manager 610 and
transmitter 630. Wireless device 600 may also include a processor
and memory. Each of these components may be in communication with
each other.
The receiver 605 may receive information which may be passed on to
other components of the device. The receiver 605 may also perform
the functions described with reference to the receiver 505 of FIG.
5. The receiver 605 may be an example of aspects of the transceiver
825 described with reference to FIG. 8.
The CCA based silencing manager 610 may be an example of aspects of
CCA based silencing manager 510 described with reference to FIG. 5.
The CCA based silencing manager 610 may include CCA component 615,
silencing signal component 620 and band switching component 625.
The CCA based silencing manager 610 may be an example of aspects of
the CCA based silencing manager 805 described with reference to
FIG. 8.
The CCA component 615 may perform a CCA in a time slot prior to a
first subframe, and determine whether a CCA in the shared RF
spectrum band has failed. In some cases, the managed RF spectrum
band comprises a portion of a system bandwidth of a WWAN.
The silencing signal component 620 may transmit a silencing signal
in the managed RF spectrum band based on the determination that a
CCA has failed, and receive a silencing signal in a managed RF
spectrum band, where the silencing signal is based on a
determination that a CCA has failed.
In some cases, transmitting the silencing signal in the managed RF
spectrum band includes transmitting the silencing signal during a
first time slot of a subframe of the managed RF spectrum band based
on the determination. In some cases, the silencing signal comprises
a multi-tone OFDM signal, a PN signal, or a CAZAC signal.
The band switching component 625 may switch from receiving
transmissions from a source of the silencing signal in the shared
RF spectrum band to receiving transmissions from the source of the
silencing signal in the managed RF spectrum band based on the
silencing signal, transmit a message in the managed RF spectrum
band based on the silencing signal, and transmit a subsequent
message in the shared RF spectrum band based on the determination
that the subsequent CCA has succeeded. In some cases, the message
comprises information for a mission critical application or for a
control application.
The transmitter 630 may transmit signals received from other
components of wireless device 600. In some examples, the
transmitter 630 may be collocated with a receiver in a transceiver
module. For example, the transmitter 630 may be an example of
aspects of the transceiver 825 described with reference to FIG. 8.
The transmitter 630 may utilize a single antenna, or it may utilize
more than one antenna.
FIG. 7 shows a block diagram of a CCA based silencing manager 700
which may be an example of the corresponding component of wireless
device 500 or wireless device 600. That is, CCA based silencing
manager 700 may be an example of aspects of CCA based silencing
manager 510 or CCA based silencing manager 610 described with
reference to FIGS. 5 and 6. The CCA based silencing manager 700 may
also be an example of aspects of the CCA based silencing manager
805 described with reference to FIG. 8.
The CCA based silencing manager 700 may include CCA component 705,
band switching component 710, resource identification component
715, silencing signal component 720 and radio powering component
725. Each of these modules may communicate, directly or indirectly,
with one another (e.g., via one or more buses).
The CCA component 705 may perform a CCA in a time slot prior to a
first subframe, and determine whether a CCA in the shared RF
spectrum band has failed.
The band switching component 710 may switch from receiving
transmissions from a source of the silencing signal in the shared
RF spectrum band to receiving transmissions from the source of the
silencing signal in the managed RF spectrum band based on the
silencing signal, transmit a message in the managed RF spectrum
band based on the silencing signal, and transmit a subsequent
message in the shared RF spectrum band based on the determination
that the subsequent CCA has succeeded.
The resource identification component 715 may identify time and
frequency resources on the managed or shared band for reception or
transmission of wireless signals. In some cases, time resources of
the managed RF spectrum band are organized according to a TDD
configuration, and the resources of the shared band may be
synchronized with those of the managed band.
The silencing signal component 720 may transmit a silencing signal
in the managed RF spectrum band based on the determination that a
CCA has failed, and receive a silencing signal in a managed RF
spectrum band, where the silencing signal is based on a
determination that a CCA has failed.
The radio powering component 725 may power up or down a radio for
the managed RF spectrum band.
FIG. 8 shows a diagram of a system 800 including a device that
supports UE silencing based on CCA in shared spectrum in accordance
with various aspects of the present disclosure. For example, system
800 may include wireless device 135-i, which may be an example of a
wireless device 500, a wireless device 600, or a wireless device
135 as described with reference to FIGS. 1, 2, and 5 through 7.
Wireless device 135-i may communicate with other devices such as
wireless device 135-j, and wireless device 135-k, which may be part
of a critical information network such as a factory automation or
home automation network.
Wireless device 135-c may also include CCA based silencing manager
805, memory 810, processor 820, transceiver 825, antenna 830 and
critical communication component 835. Each of these modules may
communicate, directly or indirectly, with one another (e.g., via
one or more buses). The CCA based silencing manager 805 may be an
example of a CCA based silencing manager as described with
reference to FIGS. 5 through 7.
The memory 810 may include random access memory (RAM) and read only
memory (ROM). The memory 810 may store computer-readable,
computer-executable software including instructions that, when
executed, cause the processor to perform various functions
described herein (e.g., UE silencing based on CCA in shared
spectrum, etc.). In some cases, the software 815 may not be
directly executable by the processor but may cause a computer
(e.g., when compiled and executed) to perform functions described
herein. The processor 820 may include an intelligent hardware
device, (e.g., a central processing unit (CPU), a microcontroller,
an application specific integrated circuit (ASIC), etc.)
The transceiver 825 may communicate bi-directionally, via one or
more antennas, wired, or wireless links, with one or more networks,
as described above. For example, the transceiver 825 may
communicate bi-directionally with a base station 105 or a UE 115.
The transceiver 825 may also include a modem to modulate the
packets and provide the modulated packets to the antennas for
transmission, and to demodulate packets received from the antennas.
In some cases, the wireless device may include one of antenna 830.
However, in some cases the device may have more than one of antenna
830, which may be capable of concurrently transmitting or receiving
multiple wireless transmissions.
The critical communication component 835 may perform
mission-critical or latency-sensitive communications, such as
closed loop control communication as part of a factory or home
automation network.
FIG. 9 shows a block diagram of a wireless device 900 that supports
UE silencing based on CCA in shared spectrum in accordance with
various aspects of the present disclosure. Wireless device 900 may
be an example of aspects of a UE 115 described with reference to
FIGS. 1 through 4. Wireless device 900 may include receiver 905, UE
communication silencing manager 910 and transmitter 915. Wireless
device 900 may also include a processor and memory. Each of these
components may be in communication with each other.
The receiver 905 may receive information such as packets, user
data, or control information associated with various information
channels (e.g., control channels, data channels, and information
related to UE silencing based on CCA in shared spectrum, etc.).
Information may be passed on to other components of the device. The
receiver 905 may be an example of aspects of the transceiver 1225
described with reference to FIG. 12.
The UE communication silencing manager 910 may identify resources
for an UL transmission associated with a first RAT operating in a
managed RF spectrum band, receive a silencing signal in the managed
RF spectrum band during a time period including the identified
resources, where the silencing signal is based on a determination
that a CCA has failed, and where a second RAT operating in a shared
RF spectrum band is synchronized with the first RAT operating in
the managed RF spectrum band, and suspend transmission in the
managed RF spectrum band during the time period based on the
silencing signal. The UE communication silencing manager 910 may
also be an example of aspects of the UE communication silencing
manager 1205 described with reference to FIG. 12.
The transmitter 915 may transmit signals received from other
components of wireless device 900. In some examples, the
transmitter 915 may be collocated with a receiver in a transceiver
module. For example, the transmitter 915 may be an example of
aspects of the transceiver 1225 described with reference to FIG.
12. The transmitter 915 may include a single antenna, or it may
include a plurality of antennas.
FIG. 10 shows a block diagram of a wireless device 1000 that
supports UE silencing based on CCA in shared spectrum in accordance
with various aspects of the present disclosure. Wireless device
1000 may be an example of aspects of a wireless device 900 or a UE
115 described with reference to FIGS. 1 through 4, and 9. Wireless
device 1000 may include receiver 1005, UE communication silencing
manager 1010 and transmitter 1030. Wireless device 1000 may also
include a processor and memory. Each of these components may be in
communication with each other.
The receiver 1005 may receive information which may be passed on to
other components of the device. The receiver 1005 may also perform
the functions described with reference to the receiver 905 of FIG.
9. The receiver 1005 may be an example of aspects of the
transceiver 1225 described with reference to FIG. 12.
The UE communication silencing manager 1010 may be an example of
aspects of UE communication silencing manager 910 described with
reference to FIG. 9. The UE communication silencing manager 1010
may include resource identifying component 1015, silencing signal
component 1020 and transmission suspension component 1025. The UE
communication silencing manager 1010 may be an example of aspects
of the UE communication silencing manager 1205 described with
reference to FIG. 12.
The resource identifying component 1015 may identify resources for
an UL transmission associated with a RAT operating in a managed RF
spectrum band.
The silencing signal component 1020 may receive a silencing signal
in the managed RF spectrum band during a time period including the
identified resources, where the silencing signal is based on a
determination that a CCA has failed, and where a second RAT
operating in a shared RF spectrum band is synchronized with the
first RAT operating in the managed RF spectrum band.
The transmission suspension component 1025 may suspend transmission
in the managed RF spectrum band during the time period based on the
silencing signal.
The transmitter 1030 may transmit signals received from other
components of wireless device 1000. In some examples, the
transmitter 1030 may be collocated with a receiver in a transceiver
module. For example, the transmitter 1030 may be an example of
aspects of the transceiver 1225 described with reference to FIG.
12. The transmitter 1030 may utilize a single antenna, or it may
utilize more than one antenna.
FIG. 11 shows a block diagram of a UE communication silencing
manager 1100 which may be an example of the corresponding component
of wireless device 900 or wireless device 1000 in accordance with
various aspects of the present disclosure. That is, UE
communication silencing manager 1100 may be an example of aspects
of UE communication silencing manager 910 or UE communication
silencing manager 1010 described with reference to FIGS. 9 and 10.
The UE communication silencing manager 1100 may also be an example
of aspects of the UE communication silencing manager 1205 described
with reference to FIG. 12.
The UE communication silencing manager 1100 may include DL
communication component 1105, UL grant component 1110, transmission
resuming component 1115, transmission suspension component 1120,
resource identifying component 1125 and silencing signal component
1130. Each of these modules may communicate, directly or
indirectly, with one another (e.g., via one or more buses).
The DL communication component 1105 may receive a DL transmission
during the time period based on the DL grant. The UL grant
component 1110 may receive an UL grant, where the resources are
identified based on the UL grant, and receive an UL grant for a
subsequent time period.
The transmission resuming component 1115 may resume transmission in
the managed RF spectrum band during the subsequent time period
based on the UL grant. The transmission suspension component 1120
may suspend transmission in the managed RF spectrum band during the
time period based on the silencing signal.
The resource identifying component 1125 may identify resources for
an UL transmission associated with a RAT operating in a managed RF
spectrum band.
The silencing signal component 1130 may receive a silencing signal
in the managed RF spectrum band during a time period including the
identified resources, where the silencing signal is based on a
determination that a CCA has failed, and where a second RAT
operating in a shared RF spectrum band is synchronized with the
first RAT operating in the managed RF spectrum band.
FIG. 12 shows a diagram of a system 1200 including a device that
supports UE silencing based on CCA in shared spectrum in accordance
with various aspects of the present disclosure. For example, system
1200 may include UE 115-d, which may be an example of a wireless
device 900, a wireless device 1000, or a UE 115 as described with
reference to FIGS. 1, 2, and 9 through 11.
UE 115-d may also include UE communication silencing manager 1205,
memory 1210, processor 1220, transceiver 1225, antenna 1230 and ECC
module 1235. Each of these modules may communicate, directly or
indirectly, with one another (e.g., via one or more buses). The UE
communication silencing manager 1205 may be an example of a UE
communication silencing manager as described with reference to
FIGS. 9 through 11.
The memory 1210 may include RAM and ROM. The memory 1210 may store
computer-readable, computer-executable software including
instructions that, when executed, cause the processor to perform
various functions described herein (e.g., UE silencing based on CCA
in shared spectrum, etc.). In some cases, the software 1215 may not
be directly executable by the processor but may cause a computer
(e.g., when compiled and executed) to perform functions described
herein.
The processor 1220 may include an intelligent hardware device,
(e.g., a CPU, a microcontroller, an ASIC, etc.) The transceiver
1225 may communicate bi-directionally, via one or more antennas,
wired, or wireless links, with one or more networks, as described
above. For example, the transceiver 1225 may communicate
bi-directionally with a base station 105 or a UE 115. The
transceiver 1225 may also include a modem to modulate the packets
and provide the modulated packets to the antennas for transmission,
and to demodulate packets received from the antennas. In some
cases, the wireless device may include one of antenna 1230.
However, in some cases the device may have more than one of antenna
830, which may be capable of concurrently transmitting or receiving
multiple wireless transmissions.
The ECC module 1235 may enable operations using eCCs such as
communication using shared or shared spectrum, using reduced TTIs
or subframe durations, or using a large number of CCs.
FIG. 13 shows a flowchart illustrating a method 1300 for UE
silencing based on CCA in shared spectrum in accordance with
various aspects of the present disclosure. The operations of method
1300 may be implemented by a device such as a wireless device 135
or its components as described with reference to FIGS. 1 and 2. For
example, the operations of method 1300 may be performed by the CCA
based silencing manager as described herein. In some examples, the
wireless device 135 may execute a set of codes to control the
functional elements of the device to perform the functions
described below. Additionally or alternatively, the wireless device
135 may perform aspects the functions described below using
special-purpose hardware.
At block 1305, the wireless device 135 may determine that a CCA in
a shared RF spectrum band has failed, where a RAT operating in the
shared RF spectrum band is synchronized with a RAT operating in a
managed RF spectrum band as described above with reference to FIGS.
2 through 4. In some examples, the operations of block 1305 may be
performed by the CCA component 615 or 705 as described with
reference to FIGS. 6 and 7.
At block 1310, the wireless device 135 may transmit a silencing
signal in the managed RF spectrum band based on the determination
as described above with reference to FIGS. 2 through 4. In some
examples, the operations of block 1310 may be performed by the
silencing signal component 620 or 720 as described with reference
to FIGS. 6 and 7.
At block 1315, the wireless device 135 may transmit a message in
the managed RF spectrum band based on the silencing signal as
described above with reference to FIGS. 2 through 4. In some
examples, the operations of block 1315 may be performed by the band
switching component 625 or 710 as described with reference to FIGS.
6 and 7.
FIG. 14 shows a flowchart illustrating a method 1400 for UE
silencing based on CCA in shared spectrum in accordance with
various aspects of the present disclosure. The operations of method
1400 may be implemented by a device such as a UE 115 or its
components as described with reference to FIGS. 1 and 2. For
example, the operations of method 1400 may be performed by the UE
communication silencing manager as described herein. In some
examples, the UE 115 may execute a set of codes to control the
functional elements of the device to perform the functions
described below. Additionally or alternatively, the UE 115 may
perform aspects the functions described below using special-purpose
hardware.
At block 1405, the UE 115 may identify resources for an UL
transmission associated with a RAT operating in a managed RF
spectrum band as described above with reference to FIGS. 2 through
4. In some examples, the operations of block 1405 may be performed
by the resource identifying component 1015 or 1125 as described
with reference to FIGS. 10 and 11.
At block 1410, the UE 115 may receive a silencing signal in the
managed RF spectrum band during a time period including the
identified resources, where the silencing signal is based on a
determination that a CCA has failed, and where a second RAT
operating in a shared RF spectrum band is synchronized with the
first RAT operating in the managed RF spectrum band as described
above with reference to FIGS. 2 through 4. In some examples, the
operations of block 1410 may be performed by the silencing signal
component 1020 or 1130 as described with reference to FIGS. 10 and
11.
At block 1415, the UE 115 may suspend transmission in the managed
RF spectrum band during the time period based on the silencing
signal as described above with reference to FIGS. 2 through 4. In
some examples, the operations of block 1415 may be performed by the
transmission suspension component as described with reference to
FIGS. 10 and 11.
FIG. 15 shows a flowchart illustrating a method 1500 for UE
silencing based on CCA in shared spectrum in accordance with
various aspects of the present disclosure. The operations of method
1500 may be implemented by a device such as a wireless device 135
or its components as described with reference to FIGS. 1 and 2. For
example, the operations of method 1500 may be performed by the CCA
based silencing manager as described herein. In some examples, the
wireless device 135 may execute a set of codes to control the
functional elements of the device to perform the functions
described below. Additionally or alternatively, the wireless device
135 may perform aspects the functions described below using
special-purpose hardware.
At block 1505, the wireless device 135 may receive a silencing
signal in a managed RF spectrum band, where the silencing signal is
based on a determination that a CCA has failed, and where a first
RAT operating in the managed RF spectrum band is synchronized with
a second RAT operating in a shared RF spectrum band as described
above with reference to FIGS. 2 through 4. In some examples, the
operations of block 1505 may be performed by the silencing signal
component 620 or 720 as described with reference to FIGS. 6 and
7.
At block 1510, the wireless device 135 may switch from receiving
transmissions from a source of the silencing signal in the shared
RF spectrum band to receiving transmissions from the source of the
silencing signal in the managed RF spectrum band based on the
silencing signal as described above with reference to FIGS. 2
through 4. In some examples, the operations of block 1510 may be
performed by the band switching component 625 or 710 as described
with reference to FIGS. 6 and 7.
It should be noted that these methods describe possible
implementation, and that the operations and the steps may be
rearranged or otherwise modified such that other implementations
are possible. In some examples, aspects from two or more of the
methods may be combined. For example, aspects of each of the
methods may include steps or aspects of the other methods, or other
steps or techniques described herein. Thus, aspects of the
disclosure may provide for UE silencing based on CCA in shared
spectrum.
The description herein is provided to enable a person skilled in
the art to make or use the disclosure. Various modifications to the
disclosure will be readily apparent to those skilled in the art,
and the generic principles defined herein may be applied to other
variations without departing from the scope of the disclosure.
Thus, the disclosure is not to be limited to the examples and
designs described herein but is to be accorded the broadest scope
consistent with the principles and novel features disclosed
herein.
The functions described herein may be implemented in hardware,
software executed by a processor, firmware, or any combination
thereof. If implemented in software executed by a processor, the
functions may be stored on or transmitted over as one or more
instructions or code on a non-transitory computer-readable medium.
Other examples and implementations are within the scope of the
disclosure and appended claims. For example, due to the nature of
software, functions described above can be implemented using
software executed by a processor, hardware, firmware, hardwiring,
or combinations of any of these. Features implementing functions
may also be physically located at various positions, including
being distributed such that portions of functions are implemented
at different physical (PHY) locations. Also, as used herein,
including in the claims, "or" as used in a list of items (for
example, a list of items prefaced by a phrase such as "at least one
of" or "one or more") indicates an inclusive list such that, for
example, a list of at least one of A, B, or C means A or B or C or
AB or AC or BC or ABC (i.e., A and B and C).
Computer-readable media includes both non-transitory computer
storage media and communication media including any medium that
facilitates transfer of a computer program from one place to
another. A non-transitory storage medium may be any available
medium that can be accessed by a general purpose or special purpose
computer. By way of example, and not limitation, non-transitory
computer-readable media can comprise RAM, ROM, electrically
erasable programmable read only memory (EEPROM), compact disk (CD)
ROM or other optical disk storage, magnetic disk storage or other
magnetic storage devices, or any other non-transitory medium that
can be used to carry or store desired program code means in the
form of instructions or data structures and that can be accessed by
a general-purpose or special-purpose computer, or a general-purpose
or special-purpose processor. Also, any connection is properly
termed a non-transitory computer-readable medium. For example, if
the software is transmitted from a website, server, or other remote
source using a coaxial cable, fiber optic cable, twisted pair,
digital subscriber line (DSL), or wireless technologies such as
infrared, radio, and microwave, then the coaxial cable, fiber optic
cable, twisted pair, DSL, or wireless technologies such as
infrared, radio, and microwave are included in the definition of
medium. Disk and disc, as used herein, include CD, laser disc,
optical disc, digital versatile disc (DVD), floppy disk and Blu-ray
disc where disks usually reproduce data magnetically, while discs
reproduce data optically with lasers. Combinations of the above are
also included within the scope of computer-readable media.
Techniques described herein may be used for various wireless
communications systems such as CDMA, TDMA, FDMA (FDMA), OFDMA
(OFDMA), single carrier frequency division multiple access
(SC-FDMA), and other systems. The terms "system" and "network" are
often used interchangeably. A CDMA system may implement a radio
technology such as CDMA2000, Universal Terrestrial Radio Access
(UTRA), etc. CDMA2000 covers IS-2000, IS-95, and IS-856 standards.
IS-2000 Releases 0 and A are commonly referred to as CDMA2000
1.times., 1.times., etc. IS-856 (TIA-856) is commonly referred to
as CDMA2000 1.times.EV-DO, High Rate Packet Data (HRPD), etc. UTRA
includes Wideband CDMA (WCDMA) and other variants of CDMA. A TDMA
system may implement a radio technology such as (Global System for
Mobile communications (GSM)). An OFDMA system may implement a radio
technology such as Ultra Mobile Broadband (UMB), Evolved UTRA
(E-UTRA), IEEE 802.11 (wireless fidelity (Wi-Fi)), IEEE 802.16
(WiMAX), IEEE 802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of
Universal Mobile Telecommunications system (Universal Mobile
Telecommunications System (UMTS)). 3GPP LTE and LTE-advanced
(LTE-A) are new releases of UMTS that use E-UTRA. UTRA, E-UTRA,
UMTS, LTE, LTE-a, and GSM are described in documents from an
organization named "3rd Generation Partnership Project" (3GPP).
CDMA2000 and UMB are described in documents from an organization
named "3rd Generation Partnership Project 2" (3GPP2). The
techniques described herein may be used for the systems and radio
technologies mentioned above as well as other systems and radio
technologies. The description herein, however, describes an LTE
system for purposes of example, and LTE terminology is used in much
of the description above, although the techniques are applicable
beyond LTE applications.
In LTE/LTE-A networks, including networks described herein, the
term evolved node B (eNB) may be generally used to describe the
base stations. The wireless communications system or systems
described herein may include a heterogeneous LTE/LTE-A network in
which different types of eNBs provide coverage for various
geographical regions. For example, each eNB or base station may
provide communication coverage for a macro cell, a small cell, or
other types of cell. The term "cell" is a 3GPP term that can be
used to describe a base station, a carrier or component carrier
(CC) associated with a base station, or a coverage area (e.g.,
sector, etc.) of a carrier or base station, depending on
context.
Base stations may include or may be referred to by those skilled in
the art as a base transceiver station, a radio base station, an
access point (AP), a radio transceiver, a NodeB, eNodeB (eNB), Home
NodeB, a Home eNodeB, or some other suitable terminology. The
geographic coverage area for a base station may be divided into
sectors making up a portion of the coverage area. The wireless
communications system or systems described herein may include base
stations of different types (e.g., macro or small cell base
stations). The UEs described herein may be able to communicate with
various types of base stations and network equipment including
macro eNBs, small cell eNBs, relay base stations, and the like.
There may be overlapping geographic coverage areas for different
technologies. In some cases, different coverage areas may be
associated with different communication technologies. In some
cases, the coverage area for one communication technology may
overlap with the coverage area associated with another technology.
Different technologies may be associated with the same base
station, or with different base stations.
A macro cell generally covers a relatively large geographic area
(e.g., several kilometers in radius) and may allow unrestricted
access by UEs with service subscriptions with the network provider.
A small cell is a lower-powered base stations, as compared with a
macro cell, that may operate in the same or different (e.g.,
shared, managed, etc.) frequency bands as macro cells. Small cells
may include pico cells, femto cells, and micro cells according to
various examples. A pico cell, for example, may cover a small
geographic area and may allow unrestricted access by UEs with
service subscriptions with the network provider. A femto cell may
also cover a small geographic area (e.g., a home) and may provide
restricted access by UEs having an association with the femto cell
(e.g., UEs in a closed subscriber group (CSG), UEs for users in the
home, and the like). An eNB for a macro cell may be referred to as
a macro eNB. An eNB for a small cell may be referred to as a small
cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB may
support one or multiple (e.g., two, three, four, and the like)
cells (e.g., CCs). A UE may be able to communicate with various
types of base stations and network equipment including macro eNBs,
small cell eNBs, relay base stations, and the like.
The wireless communications system or systems described herein may
support synchronous or asynchronous operation. For synchronous
operation, the base stations may have similar frame timing, and
transmissions from different base stations may be approximately
aligned in time. For asynchronous operation, the base stations may
have different frame timing, and transmissions from different base
stations may not be aligned in time. The techniques described
herein may be used for either synchronous or asynchronous
operations.
The DL transmissions described herein may also be called forward
link transmissions while the UL transmissions may also be called
reverse link transmissions. Each communication link described
herein including, for example, wireless communications system 100
and 200 of FIGS. 1 and 2 may include one or more carriers, where
each carrier may be a signal made up of multiple sub-carriers
(e.g., waveform signals of different frequencies). Each modulated
signal may be sent on a different sub-carrier and may carry control
information (e.g., reference signals, control channels, etc.),
overhead information, user data, etc. The communication links
described herein (e.g., communication links 125 of FIG. 1) may
transmit bidirectional communications using frequency division
duplex (FDD) (e.g., using paired spectrum resources) or TDD
operation (e.g., using unpaired spectrum resources). Frame
structures may be defined for FDD (e.g., frame structure type 1)
and TDD (e.g., frame structure type 2).
Thus, aspects of the disclosure may provide for UE silencing based
on CCA in shared spectrum. It should be noted that these methods
describe possible implementations, and that the operations and the
steps may be rearranged or otherwise modified such that other
implementations are possible. In some examples, aspects from two or
more of the methods may be combined.
The various illustrative blocks and modules described in connection
with the disclosure herein may be implemented or performed with a
general-purpose processor, a digital signal processor (DSP), an
ASIC, an field programmable gate array (FPGA) or other programmable
logic device, discrete gate or transistor logic, discrete hardware
components, or any combination thereof designed to perform the
functions described herein. A general-purpose processor may be a
microprocessor, but in the alternative, the processor may be any
conventional processor, controller, microcontroller, or state
machine. A processor may also be implemented as a combination of
computing devices (e.g., a combination of a DSP and a
microprocessor, multiple microprocessors, one or more
microprocessors in conjunction with a DSP core, or any other such
configuration). Thus, the functions described herein may be
performed by one or more other processing units (or cores), on at
least one integrated circuit (IC). In various examples, different
types of ICs may be used (e.g., Structured/Platform ASICs, an FPGA,
or another semi-custom IC), which may be programmed in any manner
known in the art. The functions of each unit may also be
implemented, in whole or in part, with instructions embodied in a
memory, formatted to be executed by one or more general or
application-specific processors.
In the appended figures, similar components or features may have
the same reference label. Further, various components of the same
type may be distinguished by following the reference label by a
dash and a second label that distinguishes among the similar
components. If just the first reference label is used in the
specification, the description is applicable to any one of the
similar components having the same first reference label
irrespective of the second reference label.
As used herein, the phrase "based on" shall not be construed as a
reference to a closed set of conditions. For example, an exemplary
step that is described as "based on condition A" may be based on
both a condition A and a condition B without departing from the
scope of the present disclosure. In other words, as used herein,
the phrase "based on" shall be construed in the same manner as the
phrase "based at least in part on."
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